Conventional approaches to the road design rely on separate design for each road system. Thus, the design of road systems usually begins with the planning stage where a civil engineer arranges the road to satisfy the standard specifications such as grade and meeting of centerlines at intersections. Then a draftsman produces an initial design using one of numerous software programs to draft profiles, vertical alignment, measure cross-sections and calculate the cut and fill quantities. In this connection, it will be appreciated that road surfaces are generally not level. Whenever a gradient is associated with the road surface, this requires that, during construction, earth be removed (“cut”) from those sections which are lower than the foundation level and that earth be added to those sections which are higher than the foundation level and must therefore be “filled”. Such earthworks require skilled operation of heavy and expensive machinery and is therefore highly costly. It is therefore desirable, as far as is possible, to equalize the cut and fill quantities so as to avoid unnecessary earthworks.
Such equalization is an iterative process requiring repeated fine-tuning by the engineer. The iteration may be repeated numerous times before the road system satisfies all of the physical constraints and the cut and fill quantities are properly balanced. Conventionally, the design has been a trial and error affair according to the experience of the civil engineer. The vertical alignment is determined for one road at a time and not for the entire road system. Earthworks of subdivision lots which border transportation routes have also not conventionally been taken into account, nor has the economical factor been properly considered.
A CAD approach to the design of rail tracks is presented by L. G. Allen et al. in “Cost Effective Design—The Use of Computer Aided Drafting In: Route Selection, Earthworks Optimisation and Rail Track Engineering” appearing in Conference on Railway Engineering, Perth/Australia, September 1987; XP-000917757. However, this article makes no reference to minimization of earthworks cost. Rather it attempts to achieve cost-effective design using an interactive CAD process. Thus, cost effectiveness is the result of user's interactive work (i.e. trial and error) and is not an automatic computerized process that uses pre-prepared data allowing the route to be optimized without any user interaction. In this respect, the CAD tools disclosed by this article are typical of prior art methods that relate on trial and error for optimizing transportation routes.